Example of how to capture group values using Regular expressions in Swift http://whatdidilearn.info/2018/07/29/how-to-capture-regex-group-values-in-swift.html

captureGroupValuesExample.swift

import UIKit

struct FilmSeries {
  var title: String
  var season: Int?
  var episode: Int?
}

var series = [
  FilmSeries(title: "Pilot", season: 1, episode: 1),
  FilmSeries(title: "The Party", season: 1, episode: 2),
  FilmSeries(title: "Season 1 Episode 3 - When Joey meets Zoey", season: nil, episode: nil)
]


func findSeasonAndEpisodeFrom(title: String) -> (Int?, Int?) {
  var seasonNumber: Int?
  var episodeNumber: Int?
  
  let pattern = "^Season\\s+(?<season>\\d+)\\s+Episode\\s+(?<episode>\\d+)"
  let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive)
  
  if let match = regex?.firstMatch(in: title, options: [], range: NSRange(location: 0, length: title.utf16.count)) {
    if let seasonRange = Range(match.range(withName: "season"), in: title) {
      seasonNumber = Int(title[seasonRange])
    }
    
    if let episodeRange = Range(match.range(withName: "episode"), in: title) {
      episodeNumber = Int(title[episodeRange])
    }
  }
  
  return (seasonNumber, episodeNumber)
}


findSeasonAndEpisodeFrom(title: "Season 1 Episode 3 - When Joey meets Zoey")
findSeasonAndEpisodeFrom(title: "Season 1 - When Joey meets Zoey")
findSeasonAndEpisodeFrom(title: "Episode 3 - When Joey meets Zoey")
findSeasonAndEpisodeFrom(title: "When Joey meets Zoey")

let updartedSeries = series.map { (series: FilmSeries) -> FilmSeries in
  if series.season == nil {
    let (season, episode) = findSeasonAndEpisodeFrom(title: series.title)
    return FilmSeries(title: series.title, season: season, episode: episode)
  }
  
  return series
}

updartedSeries